The state of the California current, 2006-2007: Regional and local processes dominate,

Description

The state of the California Current System (CCS) between Oregon and Baja California is summarized in this report, covering spring 2006 to spring 2007. Observations reported here are based on contributions from various ocean observing programs along the West Coast of North America. Basin-scale indicators were variable or neutral over the last year. This indeterminate forcing was reflected in conditions in the CCS where no coherent patterns emerged, i.e., no single "state" could be ascribed to the system. Rather, regional or local processes dominated observed patterns. Similar to last year, delayed upwelling off Oregon and central California dramatically affected higher trophic levels: euphausiid recruitment was delayed and as a likely consequence seabird productivity off Central California was extremely depressed. For example, Cassin's auklet had a complete reproductive failure, similar to 2006. Observations during the spring of 2007 demonstrate that these patterns were ephemeral since upwelling was normal and seabird productivity improved. Off southern and Baja California, upwelling-favorable winds were also weak or delayed during 2006, but biological consequences appear to have been relatively minor., Cited By (since 1996):24,
Ecology, ,

To assess the impact of California sea lions (Zalophus californianus) on salmon fisheries in the Monterey Bay region of California, the percentages of hooked fish taken by sea lions in commercial and recreational salmon fisheries were estimated from 1997 to 1999. Onboard surveys of sea lion interactions with the commercial and recreational fisheries and dockside interviews with fishermen after their return to port were conducted in the ports of Santa Cruz, Moss Landing, and Monterey. Approximately 1745 hours of onboard and dockside surveys were conducted - 924 hours in the commercial fishery and 821 hours in the recreational fishery (commercial passenger fishing vessels [CPFVs] and personal skiffs combined). Adult male California sea lions were responsible for 98.4% of the observed depredations of hooked salmon in the commercial and recreational fisheries in Monterey Bay. Mean annual percentages of hooked salmon taken by sea lions ranged from 8.5% to 28.6% in the commercial fishery, 2.2% to 18.36% in the CPFVs, and 4.0% to 17.5% in the personal skiff fishery. Depredation levels in the commercial and recreational salmon fisheries were greatest in 1998 - likely a result of the large El Niño Southern Oscillation (ENSO) event that occurred from 1997 to 1998 that reduced natural prey resources. Commercial fishermen lost an estimated $18,031-$60,570 of gear and $225,833-$498,076 worth of salmon as a result of interactions with sea lions. Approximately 1.4-6.2% of the available salmon population was removed from the system as a result of sea lion interactions with the fishery. Assessing the impact of a growing sea lion population on fisheries stocks is difficult, but may be necessary for effective fisheries management., Cited By (since 1996):9, CODEN: FSYBA, ,

A number of methods have been employed to determine the statistical significance of sediment toxicity test results. To allow consistency among comparisons, regardless of among-replicate variability, a protocol-specific approach has been used that considers protocol performance over a large number of comparisons. Ninetieth-percentile minimum significant difference (MSD) values were calculated to determine a critical threshold for statistically significant sample toxicity. Significant toxicity threshold values (as a percentage of laboratory control values) are presented for six species and nine endpoints based on data from as many
as 720 stations. These threshold values are useful for interpreting sediment toxicity data from large studies and in eliminating cases where statistical significance is assigned in individual cases because among-replicate variability is small.

The springtime stratospheric ozone (O 3) layer over the Antarctic is thinning by as much as 50 percent, resulting in increased midultraviolet (UVB) radiation reaching the surface of the Southern Ocean. There is concern that phytoplankton communities confined to near-surface waters of the marginal ice zone will be harmed by increased UVB irradiance penetrating the ocean surface, thereby altering the dynamics of Antarctic marine ecosystems. Results from a 6-week cruise (Icecolors) in the marginal ice zone of the Bellingshausen Sea in austral spring of 1990 indicated that as the O 3 layer thinned: (i) sea surface- and depth-dependent ratios of UVB irradiance (280 to 320 nanometers) to total irradiance (280 to 700 nanometers) increased and (ii) UVB inhibition of photosynthesis increased. These and other Icecolors findings suggest that O 3-dependent shifts of in-water spectral irradiances alter the balance of spectrally dependent phytoplankton processes, including photoinhibition, photoreactivation, photoprotection, and photosynthesis. A minimum 6 to 12 percent reduction in primary production associated with O 3 depletion was estimated for the duration of the cruise., Cited By (since 1996):544, CODEN: SCIEA, ,

, , , Concentrations of phytoplankton and NO, are consistently low (0.2-0.4 μg Chl a liter-1) and high (4-12 μM) in surface waters of the oceanic eastern and central equatorial Pacific, and phytoplankton populations are dominated by small solitary phytoplankton (< 10 μm). Growth rates of natural phytoplankton populations, needed to assess the relative importance of many of the processes considered important in maintaining the high-nutrient, low-phytoplankton biomass condition observed in the equatorial Pacific, were estimated by several methods. The growth rates of natural phytoplankton populations were found to be -0.7 d-1 or biomass doubling d-1 and were similar for all methods. To keep this system in its observed balance requires that loss rates approximate observed growth rates. Grazing rates, measured with a dilution grazing experiment, were high (-0.5 d-1), accounting for a large fraction of the daily production. Additions of various forms of Fe to 5-7-d incubations utilizing ultraclean techniques resulted in significant shifts in autotrophic (from picoplankton to diatom dominated) and heterotrophic assemblages between
initial samples, controls, and Fe enrichments, which were presumably due to Fe, grazing by both protistan and metazoan components, and incubation artifacts. Estimated growth rates of small pennate diatoms (2 x 10 μm) showed increases in Fe enrichments (mean ± SD = 1.60 ± 0.04 d-1) with respect to controls (mean ± SD = 1.21 ± 0.33 d-1). The growth rates of the pennate diatoms were similar to those estimated for the larger (~5 μm) size fraction of the natural populations (mean = 1.42 d-1). We hypothesize that biomass regulation of the larger size fraction of phytoplankton is by a combination of grazing, Fe limitation, and sinking and that understanding the controls over the larger phytoplankton is fundamental to unraveling the high-nutrient, low-biomass paradigm., ,

The behaviour of iron and other trace elements during the IronEx-I and PlumEx experiments in the Equatorial Pacific,

Description

Dissolved (< 0.4 μm) and particulate (0.4-5 μm and > 5 μm, leachable and refractory) trace elements were measured during the IronEx I and PlumEx experiments in October and November 1993 near the Galapagos Islands. Iron was measured in the enriched patch and at control stations over a 9 day period following fertilization. The dissolved iron was initially depleted at a rate that gave an iron half-life of 28-40 h. The loss rate gradually decreased, and dissolved iron concentrations did not decrease below about 0.25 nmol kg-1 throughout the experiment. These results were most consistent with a kinetic model that was second order in iron concentration for the scavenging removal of each iron fraction. Other trace elements measured did not change significantly either in concentration or partitioning during the IronEx I experiment. Biological production tracked iron concentrations over time, which suggests that productivity within the fertilized patch was regulated by the availability of iron. The PlumEx study consisted primarily of two transects, a meridional course to the east of the Galapagos Islands and a zonal section to the west. Surface dissolved iron was very low at all stations except those near the Galapagos Islands. Sections of trace metal and other properties distinctly confirm the upwelling of the Equatorial Undercurrent as it intersects the islands. This upwelling has a great effect on the surface distributions of the trace metals on the west side of the islands. Productivity within the mixed layer of this region is highly correlated with iron and nitrate. West of the islands highest productivity is found at stations with the highest iron. North of the Equatorial front, in nitrate-depleted waters, elevated iron concentrations do not enhance productivity., Cited By (since 1996):58, Oceanography, CODEN: DSROE, ,

For the past decade, the Marine Optical Buoy (MOBY), an autonomous radiometric buoy stationed in the waters off Lanai, Hawaii, has been the primary in-water oceanic observatory for the vicarious calibration of U. S. satellite ocean color sensors, including the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectrometer (MODIS) instruments on the National Aeronautics and Space Administration's (NASA's) Terra and Aqua satellites. The MOBY vicarious calibration of these sensors supports international efforts to develop a global, multi-year time series of consistently calibrated ocean color data products. A critical component of the MOBY program is establishing radiometric traceability to the International System of Units (SI) through standards provided by the U. S. National Institute of Standards and Technology (NIST). A detailed uncertainty budget is a core component of traceable metrology. We present the MOBY uncertainty budget for up-welling radiance and discuss approaches in new instrumentation to reduce the uncertainties in in situ water-leaving radiance measurements., Cited By (since 1996):10, Oceanography, Art. No.: 67441M, CODEN: PSISD, ,

Similarity in structural features would argue that sharks possess class I, class IIA and class IIB genes, coding for classical peptide-presenting molecules, as well as non-classical class I genes. Some aspects of shark major histocompatibility complex genes are similar to teleost genes and others are similar to tetrapod genes. Shark class I genes form a monophyletic group, as also seen for tetrapods, but the classical and nonclassical genes form two orthologous clades, as seen for teleosts. Teleost class I genes arose independently at least four different times with the nonclassical genes of ray-finned fishes and all the shark and lobe-finned fish class I genes forming 1 clade. The ray-finned fish classical class I genes arose separately. In phylogenetic trees of class II α2 and β2 domains, the shark and tetrapod genes cluster more closely than the teleost genes and, unlike the teleost sequences, the class II α1 domains of sharks and tetrapods lack cysteines. On the other hand, both shark and teleost genes display sequence motifs in the antigen-binding cleft that have persisted over very long time periods. The similarities may reflect common selective pressures on species in aqueous environments while differences may be due to different evolutionary rates., Cited By (since 1996):19, CODEN: IMRED, ,

The flux of dissolved iron from sediments to the water column was measured with flux chambers along the California coast over a five-year period. High fluxes were observed from sediments on the continental shelf. The measured fluxes were an average of 75 times larger than flux values derived from pore-water iron gradients. The iron flux was significantly correlated with the oxidation of organic matter, which allows an extrapolation to the global shelf. The input from shelf sediments is at least as significant as the global input of dissolved iron from aerosols, which has been presumed to be the dominant external iron source. Evidence of this input is seen 100's of kilometers offshore where it can enable the high productivity of broad coastal regions seen in satellite images. Copyright 2004 by the American Geophysical Union., Cited By (since 1996):125, Oceanography, CODEN: GPRLA, ,

Big Creek Marine Ecological Reserve (BCER), located off the central California coast, has been closed to fishing since January 1994. We used side scan sonar and an occupied submersible to collect baseline information on species-habitat relationships, density, and species and size composition of fish inside and outside BCER. Forty-three dives were made in the fall of 1997 and 1998, at depths of 20-250 m. From 142 video transects, we identified over 70,000 fish from 82 taxa, including 36 species of rockfish. About 93% of the 25,159 fish inside BCER were rockfishes representing at least 20 species. Young-of-the-year rockfishes dominated rock outcrops in 20-90 m depth inside and outside BCER. Four distinct fish assemblages were associated with (1) fine, smooth sediment in deep water; (2) bedrock with uneven surface in deep water; (3) sand waves and shell hash in shallow water; and (4) boulders and organic habitats on rock in shallow water. There were no significant differences in fish density among locations (inside and outside BCER) and depths or between years. Density was significantly higher in high-relief rock habitat than in low-relief soft and mixed sediments, regardless of location. There were no consistent patterns of larger fish inside compared to outside the protected area. We recommend development of a monitoring program to continue these surveys after increased time of protection and with increased assessment effort in the appropriate habitats of economically valuable species. In addition, extending the boundaries of BCER seaward would protect habitats and fish in water depths greater than 100 m., Cited By (since 1996):18, , , Downloaded from: http://calcofi.org/publications/ccreports.html (05 June 14).

The validity of using morphological characteristics as predictors of age in the kelp, Pterygophora californica (Laminariales, Phaeophyta),

Description

Previous studies have used stipe ring counts to estimate the age of several species in the
Laminariales. Although this method is widely accepted, it has rarely been validated. To test the validity
of aging Pterygophora californica by counting rings formed in the stipe, we sampled plants of known
age between 1.0 and 4.4 yr old and plants with a calculated age of 12 yr. For a given cohort, the number
of complete rings closely approximated the known age in years. indicating ring counts are a reliable
method for estimating the age structure of P califomica populations. However, ring counts from
individual plants of known age can vary by ± 2 yr (95 % CI), and among readers counting the same
plants by ± 1 yr (95 % CI). Single plants, there fore, could not be reliably aged by ring counts Linear
relationships between 2 morphometric measures (stipe length and stipe diameter) and number of rings
varied both within and between stands and sites, suggesting these measures are not reliable for
estimating the age of this alga in the areas sampled. Stand density may be an important factor
contributing to the variation in these morphome tric measures. Short-term (22 wk) field manipulations of
stand density showed that plants at high density (30 plants m^-2) grew faster in stipe length and slower in
stipe diameter than those at medium (6 plants m^-2) and low (2 plants m^-2) densities. Plants collected in a multi-site survey, however, showed no relationship between stand density and stipe morphology,
indicating factors other than density also influence stipe growth Short-term (22 wk) field manipulations,
which reduced ambient light levels by up to 58 %. had no significant effects on stipe morphology., , ,

An improved radiometric aging technique was used to examine annulus-derived age estimates from otoliths of the Atlantic tarpon, Megalops atlanticus. Whole otoliths from juvenile fish and otolith cores, representing the first 2 years of growth, from adult fish were used to determine 210Pb and 226Ra activity; six age groups consisting of pooled otoliths and nine individual otolith cores were aged. This unprecedented use of individual otolith cores to determine age was possible because of improvements made to the 226Ra determination technique. The disequilibria of 210Pb:226Ra for these samples were used to determine radiometric age. Annulus-derived age estimates did not agree closely with radiometric age determinations. In most cases, the precision (CV≤12%) among the otolith readings could not explain the differences. The greatest radiometric age was 78.0 yr for a 2045-mm-FL female, where the radiometric error encompassed the annulus-derived age estimate of 55 yr by about 4 yr. The greatest radiometric age for males was 41.0 yr for a 1588-mm-FL tarpon, where the radiometric error encompassed the annulus-derived age estimate of 32 yr by 1 yr. Radiometric age determinations in this study indicated that the interpretation of growth zones in Atlantic tarpon otoliths can be difficult, and in some cases may be inaccurate. This study provides conclusive evidence that the longevity of the Atlantic tarpon is greater than 30 years for males and greater than 50 years for females., Cited By (since 1996):9, CODEN: FSYBA, ,

Brittle star distribution patterns and population densities on the continental slope off central California (Echinodermata: Ophiuroidea),

Description

The ophiuroid communities on the continental slope off central California were examined using box cores and trawls. Box cores were taken between 550 and 3085 m at sites southwest of the Farallon Islands, and otter and beam trawls were used below 2300 m at three sites between the Farallon Islands and Point Sur. Eighteen ophiuroid species from six families were identified. Eighty percent of the individuals collected with box cores belonged to two species, Ophiura leptoctenia and Ophiacantha normani, which were dominant between 1000 and 2000 m. The largest ophiuroid faunal break occurred at around 2000 m and was associated with elevated dissolved oxygen levels, decreasing sediment grain size, and increasing sediment organic content. A comparison of box-core and trawl data from below 2300 m showed that box cores undersampled the ophiuroid community on the continental slope, missing almost 50% of the species collected by trawls within the same area, whereas trawls underestimated ophiuroid densities, reporting on average 243 times fewer ophiuroids per m2 than did box cores. There was a change in species relative abundance patterns between sampling locations. Ophiuroids exhibited patchy spatial distribution patterns on both a small scale of around 0.1 m2 and a large scale on the order of 100-1000 s of square meters. (C) 2000 Elsevier Science Ltd., Cited By (since 1996):14,
Invertebrates, CODEN: DSROE, ,